[c-nsp] WS-X6716-10G local switching and etherchanneling

Sam Stickland sam_mailinglists at spacething.org
Fri Jul 3 05:43:40 EDT 2009


Thanks the reply Tim,

Are the port's similarly oversubscribed on the 6708, or can line-rate be 
achieved between ports 1-4 & 5-6?

Sam

Tim Stevenson wrote:
> Sam, please see inline below:
>
> At 04:38 AM 7/2/2009, Sam Stickland contended:
>
>> Hi,
>>
>> I've read:
>> http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper0900aecd80673385.html 
>>
>>
>> If I'm understanding this correctly, 
>
> I don't see any mention of 6716 in this white paper. 6716 does not 
> share the same architecture as any other 10G cards (eg 6708) mentioned 
> there. 6716 is actually more like a 6704 front ended by 4:1 muxes (at 
> a high level - in reality, different chips are being used, ie, metro & 
> r2d2 et al, not janus & rohini).
>
>> communication between each bank of
>> 8 ports on a 6716-10G will be line-rate, but communication between the
>> first and second groups of 8 ports will need to traverse the switch 
>> fabric?
>
> While it's correct that ports 1-8 & 9-16 are on separate fabric 
> channels, the key in the 6716 is that there is built-in *port-based* 
> 4:1 oversubscription.
>
> In other words, 4 physical 10G ports feed into a single 10G chip 
> (there are 4 such 10G chips on the card), ie, 4 ports share 10G of 
> bandwidth at the port level.
>
> So the maximum local switching performance you'd see in one half of 
> the card is 20G, the same as you'd get into the fabric.
>
>> On a similar note, if I create an etherchannel between two 6716-10G's
>> will a module favour forwarding out of it's locally attached channel 
>> member?
>
> No, it's just a hash decision - luck of the draw. Eg, packet comes in 
> on t1/1 and channel member ports are t1/5 and t2/5. You've basically 
> got a 50/50 chance that you'd pass over the fabric.
>
> HTH,
> Tim
>
>
>
>> Regards,
>>
>> Sam
>> _______________________________________________
>> cisco-nsp mailing list  cisco-nsp at puck.nether.net
>> https://puck.nether.net/mailman/listinfo/cisco-nsp
>> archive at http://puck.nether.net/pipermail/cisco-nsp/
>
>
>
> Tim Stevenson, tstevens at cisco.com
> Routing & Switching CCIE #5561
> Technical Marketing Engineer, Cisco Nexus 7000
> Cisco - http://www.cisco.com
> <http://www.cisco.com/>IP Phone: 408-526-6759
> ********************************************************
> The contents of this message may be *Cisco Confidential*
> and are intended for the specified recipients only.
>



More information about the cisco-nsp mailing list